The invention relates to transmitting electronic mail (e-mail) between the Internet and a mobile station.
The invention is described in connection with a GSM system (or its derivatives, such as a DCS/GSM1800), at first with reference to FIG. 1. The user of a mobile station (MS) communicates with a Mobile Switching Centre MSC through a Base Station Subsystem BSS, and with other mobile stations through the MSC, or with terminals of a wired network through a Public Switching Telephone Network PSTN. A Short Message Service Centre SMSC through which text messages, i.e. short messages, can be transmitted and received, is connected to the GSM system.
The use of Internet in transmitting e-mail is rapidly becoming popular. FIG. 1 illustrates an e-mail server 13 connected to the Internet 12, and a personal computer B connected to this server (e.g. through a local area network). (Reference B refers to a second party of a call, i.e. what is known as subscriber B.) A light and easily portable mobile station would in many respects be an ideal terminal for using e-mail.
A problem is the incompatibility between the short message function of the GSM system and Internet concerning e-mail addresses. As is known, in the GSM system short messages are transmitted using the recipient""s ISDN number. The length of a short message is limited to 160 characters. The recipient""s ISDN number is not included in these 160 characters. In the Internet the e-mail addresses are of the following format: xe2x80x9cuser@server.domainxe2x80x9d. Here the xe2x80x9cuserxe2x80x9d typically stands for a person""s first name and surname, the xe2x80x9cserverxe2x80x9d consists of the name of a company or an organization and the xe2x80x9cdomainxe2x80x9d represents the naming domain of servers indicating the type of organization (for example xe2x80x9c.comxe2x80x9d, xe2x80x9corgxe2x80x9d etc) or the country ID (for example xe2x80x9c.fixe2x80x9d, xe2x80x9c.dexe2x80x9d, etc). In FIG. 1 such Internet addresses are for instance the address of the short message service centre SMSC IASMSC xe2x80x9csmsc.operator.domainxe2x80x9d, the address of the e-mail server 13 xe2x80x9cserver.domainxe2x80x9d and computer B in its domain and having the address IAB xe2x80x9cpc.user@server.domainxe2x80x9d.
Using Internet addresses in connection with a short message function causes several problems. As prior art methods allow such an address to be transmitted only as a part of the short message contents, this would use the maximum length of the short message (as much as tens of charactLers), which in all is 160 characters. In addition, the input of long user IDs and special characters (such as @) from a mobile station keyboard is known to be difficult. Furthermore, the address books, or address lists, of current mobile stations are not designed to store Internet-formatted e-mail addresses. A further problem is that the user of computer B cannot use the reply function of the e-mail program, as the identifier of the mobile station MS and the Internet address of computer B are incompatible.
An intermediate object of the invention is to create a method and an equipment for implementing the method of converting the addresses between the short message function of a mobile communication system and the Internet. The intermediate object is achieved with a method and a system which are characterized in what is disclosed in the independent claims. A main object of the invention and preferred embodiments of the intermediate object are achieved with the methods and systems that are disclosed in the dependent claims.
The idea of the invention is that a virtual number is reserved for the Internet-format e-mail address. It is called a virtual subscriber number (a virtual number VN for short), as it is not directly associated with a physical subscriber or a terminal. The virtual subscriber number is converted into an Internet address in the fixed part of the mobile communication system, most conveniently in the short message service centre.
It is highly preferable that the virtual numbers are allocated to combinations comprising both the ID of the mobile station (MSISDN) and the Internet address of subscriber B. It is thus possible to use the same virtual numbers for different mobile stations, a few characters sufficing as the length of an individual virtual number. If the length of a virtual number is three digits, each mobile station can have 1000 such combinations at its disposal. Three digits (and a possible space or another separator in the mobile terminating messages) do not take up much of the maximum length of the short message. If several mobile stations use the same virtual number, the right recipient can in any case be deduced, as two identical combinations cannot exist. Another advantage of this kind of combinations is that they help verifying the ID of the sender of the message. An unauthorized person cannot exploit a virtual number possibly known to him.
The invention provides a flexible mechanism for creating addresses between the short message function of a mobile communication system and the Internet. A mechanism as described in the invention takes up only a very small part of the maximum length of a mobile terminating short message, i.e. the number of characters equalling the length of the virtual number. An addressing mechanism of the invention does not take up any of the length of a mobile originating short message. Furthermore, the addressing mechanism of the invention is fully compatible with current mobile stations and their address books.